Removable PCB Signal Extraction Circuit for High-Speed Memory Testing
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Solution Overview
Problem
High-speed memory applications face challenges in maintaining signal integrity when probing signals between a device under test and automatic test equipment, as existing solutions like probing back of non-backdrilled vias or implementing probe traces on test fixture PCBs significantly impact signal integrity and are difficult to remove.
Innovation Solution
A printed circuit board with first and second terminals for contacting the device under test and automatic test equipment, respectively, along with transmission lines and an extracting circuit, which includes a resistor or resistor network to minimize signal loss to less than 6 dB, allowing for effective signal extraction without degrading signal integrity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If probing is implemented on the test fixture PCB or via back of non-backdrilled vias, then signal extraction is enabled, but signal integrity is significantly degraded
Solution Approach 1:
A removable printed circuit board is introduced as an intermediary component between the device under test and the automatic test equipment. This intermediary board contains the probing circuitry and extracting circuit, allowing signal extraction without directly modifying the test fixture PCB or probing through vias that would degrade signal integrity. The intermediary board can be removed when not needed, restoring full signal integrity for production testing.
Solution Approach 2:
The testing system is segmented into separate functional components: the device under test, the removable printed circuit board with probing capabilities, and the automatic test equipment. This segmentation allows the probing and extracting circuits to be isolated on a separate board that can be selectively inserted or removed, preventing signal integrity degradation during production testing while enabling detailed signal analysis during development and debugging phases.
2Measurement precision
If probe traces and circuitry are implemented on the test fixture PCB, then signal extraction is possible, but the setup cannot be easily removed and impacts device performance
Solution Approach 1:
The probing setup transitions from a static, permanently integrated PCB trace configuration to a dynamic, removable printed circuit board configuration. The removable board can be inserted when signal extraction is needed for development and debugging, and removed when full performance is required for production testing, making the system adaptable to different operational requirements.
Solution Approach 2:
The probing circuitry is segmented from the main test fixture PCB and placed on a separate removable printed circuit board. This segmentation enables the probing capabilities to be selectively activated only when needed, without permanently impacting the test fixture or device under test, thereby providing flexibility and adaptability.
3Measurement precision
If probing is implemented to extract signals, then signal measurement is enabled, but insertion loss increases significantly
Solution Approach 1:
The removable printed circuit board acts as an intermediary with carefully designed transmission lines and buffering circuits that minimize insertion loss. The board includes proper impedance matching and signal conditioning circuits that allow signal extraction while maintaining signal strength and integrity, reducing the energy loss that would occur with direct probing methods.
Data Source
AI summary
A printed circuit board has first terminals for contacting terminals of a socket, second terminals for contacting terminals of a test fixture of an automatic test equipment, which are adapted for contacting the terminals of the socket of a device under test, transmission lines for connecting the first terminals and the terminals, and an extracting circuit electrically coupled to one of the transmission lines and configured to extract the signal being exchanged between the device under test and the automatic test equipment. The extracting circuit has a resistor or an electrical resistor network, wherein a loss added on the signal being exchanged between the device under test and the automatic test equipment over the one transmission line due to the presence of the printed circuit board is smaller than 6 dB.